Trailer coupling having a receiving sleeve

ABSTRACT

The invention relates to a trailer coupling for a motor vehicle (11), in particular a passenger car, comprising a retainer (20), which is arranged on or can be fastened to the motor vehicle (11), and a retainer part (30), which can be detachably fastened to the retainer (20) and which has a retainer insertion projection (33) for inserting into a retainer insertion receptacle (24) of the retainer (20), wherein the retainer part (30) has an integrated locking device (70) having at least one locking body (71) and has an actuation body (73), which is supported in the retainer part (30) so as to be movable in order to actuate the at least one locking body (71) into a locking position (R), wherein the at least one locking body (71) interlockingly engages in a locking receptacle (72) on the retainer (20) in the locking position (R) and is moved out of the locking receptacle (72) in a detaching position (L), the retainer insertion projection (33) of the retainer part (30) therefore being interlockingly locked in the retainer insertion receptacle (24) of the retainer (20) in the locking position (R) of the at least one locking body (71) and being removable from the retainer insertion receptacle (24) of the retainer (20) in the detaching position (L), wherein the retainer part (30) is provided for forming a coupling arm (15), which has a coupling part (60) having a coupling element (65), in particular having a coupling ball, for coupling a load carrier (200) or a trailer, or is provided for directly coupling a load carrier (200). According to the invention, the retainer part (30) has a receiving sleeve (40) having a tubular coupling insertion receptacle (41) for inserting a coupling insertion projection (66; 266) of the coupling part (60) or of the load carrier (200).

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. Utility application Ser. No.16/915,013 filed on Jun. 29, 2020, entitled “TRAILER COUPLING HAVING ARECEIVING SLEEVE,” now U.S. Pat. No. 10,696,110, dated Jun. 30, 2020,which is a 35 U.S.C. 371 national stage filing and claims priority topending International Application No. PCT/EP2016/063956 filed on Jun.16, 2016, entitled “TRAILER COUPLING HAVING A RECEIVING SLEEVE,” whichclaims the benefit of Foreign Patent Application No. DE202015103207.2filed on Jun. 17, 2015, the International Application No.PCT/EP2016/063956 and Foreign Patent Application No. DE202015103207.2are incorporated by reference herein.

The invention relates to a trailer coupling for a motor vehicle, inparticular a passenger car, comprising a retainer which is arranged onor can be fastened to the motor vehicle, and a retainer part, which canbe detachably fastened to the retainer and which has a retainerinsertion projection for inserting into a retainer insertion receptacleof the retainer, wherein the retainer part has an integrated lockingdevice having at least one locking body and has an actuation body, whichis supported in the retainer part so as to be movable in order toactuate the at least one locking body into a locking position, whereinthe at least one locking body interlocklingly engages in a lockingreceptacle on the retainer in the locking position and is moved out ofthe locking receptacle in a detaching position, wherein the retainerpart is provided for forming a coupling arm, which has a coupling parthaving a coupling element, in particular a coupling ball, for coupling aload carrier or a trailer, or for directly coupling a load carrier.

A trailer coupling of this type is explained in DE 10 2011 009 306 A1.The known trailer coupling can be adapted to various requirements sothat different coupling elements can be mounted, for example. However,the flexibility of the known trailer coupling is still not ideal.

The objective of the present invention is therefore to provide animproved trailer coupling.

In order to achieve this objective, provision is made in the case of theaforementioned type of trailer couplings that the retainer part has areceiving sleeve with a tubular coupling insertion receptacle forinserting a coupling insertion projection of the coupling part or of theload carrier.

The following is also part of the invention: trailer coupling for amotor vehicle, in particular a passenger motor vehicle, having aretainer arranged on or fastened to the motor vehicle and a coupling armdetachably fastened to the retainer, wherein the coupling arm comprisesa retainer part with an insertion projection for insertion into aretainer insertion receptacle of the retainer and a coupling part with acoupling element, in particular a coupling ball, for coupling a loadcarrier or a trailer, or is provided for direct coupling of a loadcarrier, wherein the retainer part has an integrated locking devicehaving at least one locking body and an actuation body, which issupported in the retainer part so as to be movable in order to actuatethe at least one locking body into a locking position, wherein thelocking body interlockingly engages in a locking receptacle on theretainer in the locking position and is moved out of the lockingreceptacle in a detaching position, the retainer insertion projection ofthe retainer part therefore being interlockingly locked in the retainerinsertion receptacle of the retainer in the locking position of the atleast one locking body and being removable from the retainer insertionreceptacle of the retainer in the detaching position. Provision is madein the trailer coupling that the retainer part has a receiving sleevewith a tubular coupling insertion receptacle for inserting a couplinginsertion projection of the coupling part or of the load carrier.

The coupling arm, i.e. the retainer part and the coupling part, can formparts of the trailer coupling.

It is also possible that the coupling part and the trailer couplingexplained above form components of a system. Furthermore, it is possiblethat said system or a different system comprises firstly the trailercoupling according to claim 1 and secondly a load carrier and/or anadapter element of the load carrier which has the coupling insertionprojection.

The advantage of this design is that the retainer part can be easilyremoved from the securely mounted retainer from the vehicle side, namelyby releasing the locking device. The movable components of the lockingdevice are arranged on the retainer part such that complicated andexpensive installations on the motor vehicle are not necessary. Nomovable components of a locking device need to be fitted or installed onthe motor vehicle for example. The retainer is generally hidden behindthe vehicle bumper such that it is not directly accessible. If a lockingdevice is then arranged directly on the motor vehicle in this region,Bowden cables, electrical cables or similar have to be fitted in a morecircuitous manner, in the boot, for example, where corresponding handlesor similar for actuating the locking device can be arranged. This is notthe case with the invention.

Advantageously, all the movable components of the locking device arearranged on the retainer part, i.e. on a component of the coupling armwhich can be removed from the retainer.

A manual actuation device, in particular on board the retainer part, isadvantageous for actuating the at least one locking body. Preferably aturning knob, actuating lever or similar is provided for actuating thelocking body. In any case, a manual actuation handle to actuate thelocking device, in particular towards the release position, isadvantageously a component of the coupling arm, in particular of theretainer part.

The receiving sleeve is suitable for fitting the most diverse couplingparts, but also a load carrier directly. A coupling part with aball-shaped coupling element, namely a coupling ball, can be insertedinto the receiving sleeve, for instance. A load carrier can be attachedto the coupling element, however typically a trailer can be attached.

However, it is also possible that the coupling part itself has areceiving sleeve into which a load carrier can then be inserted forexample.

Furthermore, it is possible that at least one coupling insertionprojection is provided on a load carrier which can be inserted into thecoupling insertion receptacle of the receiving sleeve. The retainer partaccording to the invention can therefore be inserted into thevehicle-side retainer as an intermediate piece to then enable fitting ofa load carrier, the coupling insertion projection of which is insertedinto the coupling insertion receptacle of the receiving sleeve. It ispossible in this case that a trailer coupling according to the inventionis provided approximately transversely centrally at the rear of thevehicle, for example, into which the load carrier can be insertedcentrally so to speak. It is also possible, however, that two or moretrailer couplings according to the invention are provided at the rear ofthe vehicle so that a load carrier with two supporting arms, on each ofwhich a coupling insertion projection is provided, can be inserted intothe respective receiving sleeve of the retainer part. The retainer partsare arranged on a carrier assembly at the same distance from thetransverse centre of the motor vehicle.

It should be noted at this point that a carrier assembly, in particulara cross member, to which the vehicle-side retainer is fastened, can ofcourse also form an integral part of the trailer coupling according tothe invention.

In order that the coupling insertion projection cannot be pushed freelythrough the receiving sleeve, but stops there at a predefined insertiondepth, an end stop is advantageously provided for a free front side ofthe coupling insertion projection on an internal cross section of thecoupling insertion receptacle. The coupling insertion receptacle has abase against which the free front side of the coupling insertionprojection strikes. The base can be a complete base forming the bottomarea of the coupling insertion receptacle such that the couplinginsertion receptacle is completely closed on the bottom side. It is alsopossible, however, that the base is only present in part, i.e. that asupporting element protrudes in the direction of the internal crosssection of the coupling insertion receptacle and forms a partial baseregion there. Said supporting element then acts as an end stop.

A different version, also in combination with the above-mentionedversion of the invention, advantageously makes provision that a stop isprovided on the outer circumference of the coupling insertion projectionfor striking a free front side of the receiving sleeve. The stop on theouter circumference of the coupling insertion projection can beconfigured like a flange, for example. It is also possible, however,that the stop is formed by a protruding interlocking element, inparticular a bolt or similar. The free front side of the receivingsleeve acting as a stop can be formed by the peripheral wall of thereceiving sleeve for example. Consequently, the stop of the couplinginsertion projection strikes the front side of the peripheral wall ofthe receiving sleeve.

Reinforcement or a dedicated stop on the front side of the receivingsleeve, in particular the peripheral wall thereof, is also advantageousas follows. It is possible that a flange projection, in particular aflange projection surrounding the free front side in a circular manner,is arranged on the free front side of the receiving sleeve to strike thecoupling insertion projection.

The receiving sleeve can be formed by a tubular element. A sufficientlystrong pipe or a sufficiently thick pipe wall are enough to guaranteethe required stability.

An advantageous embodiment of the invention makes the provision that thereceiving sleeve is reinforced by at least one reinforcing element.Reinforcing ribs or stiffening ribs are provided on a tubular body ofthe receiving sleeve, for example.

A preferred embodiment of the invention makes the provision that thereceiving sleeve is reinforced by at least one reinforcing ring. Thereinforcing ring acts as a stiffener. Advantageously, the reinforcingring completely encloses the external perimeter of the receiving sleeveor a tubular piece or tubular body of the receiving sleeve. Areinforcing ring, which is configured only as a partial ring, i.e. doesnot enclose the entire external perimeter of the tubular piece ortubular body of the receiving sleeve, is also conceivable.

An advantageous embodiment makes the provision that the at least onereinforcing ring is arranged on a free front side of the receivingsleeve. Thus, reinforcement is provided exactly where the heaviestloading by the coupling part or the load carrier may occur. Thereinforcing ring can display an additional function at this point,namely as a longitudinal stop for the coupling projection of thecoupling part or load carrier.

Preferably, a locking arrangement is provided to lock the couplinginsertion projection to the coupling insertion receptacle.

The locking arrangement advantageously comprises a locking element, forexample a locking bar, bolt or similar, which can be inserted into alocking receptacle of the receiving sleeve or pushed through the lockingreceptacle.

It would be possible for example that the locking arrangement isconfigured similar to the one which is provided on the retainerinsertion receptacle and the retainer insertion projection and iseffective. However, the locking arrangement explained below ispreferred.

The locking arrangement comprises, for example, a locking element, whichcan be inserted into a locking receptacle of the receiving sleeve orpushed through the locking receptacle. Advantageously, a plurality oflocking receptacles, in particular push-through openings, are providedon the receiving sleeve. Pairs of push-through openings, which arelocated opposite each other or are flush with each other, are preferredso that the locking element can be pushed through said lockingreceptacles. The respective longitudinal ends of the locking element areangled or can be secured by a securing element, for example a circularcotter pin or similar.

A preferred embodiment of the invention makes the provision that lockingreceptacles are provided on the coupling insertion projection and thecoupling insertion receptacle, which are flush with each other when thecoupling insertion projection is inserted into the coupling insertionreceptacle. The locking element can be pushed through the lockingreceptacle. A push-through opening is provided for the locking elementon the coupling insertion projection, for example, which penetrates saidpush-through opening as well as further push-through openings providedas locking receptacles on the receiving sleeve. Thus, the couplinginsertion projection can no longer be removed from the couplinginsertion receptacle.

It is preferred if the coupling insertion receptacle and the couplinginsertion projection have at least one anti-rotation contour forreceiving the coupling insertion projection in the coupling insertionreceptacle in a rotationally locked manner. An anti-rotation projectioncan be provided eccentric to the axis of insertion, for example. It ispreferred if the coupling insertion receptacle and the couplinginsertion projection have a polygonal cross section, for example atriangular or square cross section, in order to guarantee anti-rotation.A rectangular, in particular squarish cross section, is preferred. Thismeans that corners or corner regions can be rounded so that the couplinginsertion projection can be easily inserted into the coupling insertionreceptacle.

The axis of insertion of the coupling insertion receptacle and the axisof insertion of the retainer insertion receptacle are advantageouslyangled, for instance at right-angles. However, angles deviating from aright angle, for example, angle of 80 or 110°, are also advantageous. Inany case, the effective axes with which the coupling insertionreceptacle and the coupling insertion projection on the one hand and theretainer insertion receptacle and retainer insertion projection on theother hand can be engaged or disengaged, are preferably angled relativeto each other. An angle of 50°, for example, also ensures that an actionof force, in the longitudinal direction of the vehicle, between thecoupling insertion receptacle and the coupling insertion projection,does not act simultaneously as a force to pull the retainer insertionprojection out of the retainer insertion receptacle.

A preferred embodiment of the invention, which is also shown in moredetail in the drawings, makes the provision that an axis of insertion ofthe coupling insertion receptacle runs substantially in a horizontaldirection. It is advantageous in the case of the retainer insertionreceptacle and the retainer insertion projection if the axis ofinsertion runs substantially in a vertical direction. The vehicle-sideretainer can thus be easily accommodated behind a bumper of the vehicle,for example, and the coupling part can be inserted into the vehicle-sideretainer from below. Operation is easy and the arrangement is visuallyappealing.

It is possible that the receiving sleeve forms an integral part of theretainer part. It can be formed integrally by a retainer body of theretainer part, for example. The retainer body is a cast part or forgedpart, for example, on which the receiving sleeve is configured as asleeve section.

An advantageous embodiment of the invention makes the provision that thereceiving sleeve is detachably fastened to the retainer part, forexample screwed, riveted or similar to the retainer part. The retainerpart can thus be optionally provided with different receiving sleeves,for example, receiving sleeves with different cross sections. Fitting issimple and changeover is easy.

A preferred version of the invention makes the provision that theretainer part has a bifurcate attachment which holds the receivingsleeve. The receiving sleeve is pushed into the bifurcate attachmentfrom below or from the front (depending on the position in which it isfitted on the vehicle). It can be secured or permanently fastened thereusing a screw and/or glued and/or welded or similar.

The bifurcate attachment can have prong-like arms or side arms, forexample, which protrude downwards from the retainer insertionprojection, i.e. towards the road (depending on the position in which itis fitted on the vehicle).

In other cases referred to above, if the receiving sleeve is pushed intothe bifurcate attachment from the front, the bifurcate attachment hasprong-like arms or legs protruding horizontally from the retainerinsertion projection between which the receiving sleeve is accommodated.

It is advantageous if the attachment has side arms or legs against whichwalls, for example side walls, of the receiving sleeve rest.

In addition, it is advantageous if the attachment has a base againstwhich the receiving sleeve rests.

The attachment for the receiving sleeve can also be ring-shaped so thatthe receiving sleeve can be inserted into the attachment.

It is advantageous in any case if a receiving space, which is defined bythe attachment, accommodates a large part of the cross section of thereceiving sleeve, while a smaller part of the cross section of thereceiving sleeve protrudes from the attachment or is not accommodated inthe receiving space.

The arms of the bifurcate attachment extend in a longitudinal directionaway from a base of the attachment. A section of the receiving sleeveprotruding from the arms is preferably shorter in relation to saidlongitudinal extension than a section of the receiving sleeveaccommodated between the arms. In other words, it is advantageous if alarger part of the receiving sleeve in relation to a longitudinalextension of the arms of the attachment is arranged between the arms anda smaller part of the receiving sleeve protrudes from the arms.

It is advantageous in the case of a ring-shaped or bifurcate attachment,if provision is made that the receiving sleeve is supported on at leastthree sides of the attachment angled relative to each other.

The bifurcate attachment or also a ring-shaped attachment has prong-likearms or legs protruding from the retainer insertion projections of theretainer part.

The attachment, i.e. prong-like arms and legs, for example, preferablyforms a single piece with the retainer insertion projection.

A preferred concept also makes provision that the receiving sleeve isarranged on the retainer insertion projection as below or a body of theretainer part, for example an arm body of the retainer part, which hasthe retainer insertion projection, has the following configuration:

Preferably provision is made that the receiving sleeve is arranged onthe retainer insertion projection such that in the state of beingmounted on the vehicle it protrudes from the retainer insertionprojection towards a bumper of the motor vehicle and/or from theretainer insertion projection backwards contrary to a forward directionof travel of the motor vehicle.

Therefore, in the direction of travel of the motor vehicle, thereceiving sleeve advantageously protrudes backwards from the retainerinsertion projection. A substantially right-angled or L-shapedarrangement of retainer insertion projection and receiving sleeve isrealised, for example. An insertion section or insertion arm of the loadcarrier or of the coupling part having the coupling insertion projectioncan be short, for example.

In the state of being mounted on the vehicle, the receiving sleeveadvantageously protrudes from a bumper or rear end of the motor vehicle.

Furthermore, it is advantageous if an insertion opening of the receivingsleeve in the state of being mounted on the vehicle protrudes backwardsand/or freely from a bumper of the vehicle. This measure means that thecoupling part or the load carrier can be easily inserted into thereceiving sleeve.

Advantageously, the retainer part can also have multiple parts and abase part as well as a receiving part, which can be connected to eachother using flange parts. The flange parts support each other withsupporting surfaces and can be screwed together by means of a screwassembly.

The receiving part can be fitted on the base part preferably at leasttwo different distances in relation to a road surface. The supportingsurfaces or at least one supporting surface, advantageously thesupporting surface of the flange part of the base part, have in terms ofthe longitudinal extension thereof such a length that the respectiveother flange part can be fitted on said flange part in two longitudinalmounting positions, and the receiving sleeve or that the receiving partbearing the receiving sleeve can be fitted on the base part at least twodifferent distances from a road surface.

Advantageously, provision is made that the receiving sleeve is supportedon the rear side thereof by a flange part opposite to an insertionopening for the coupling insertion projection.

Example embodiments of the invention are explained below by means ofdrawings.

FIG. 1 shows a perspective oblique view of a trailer coupling accordingto the invention with an implied coupling part,

FIG. 2 shows a frontal view of the trailer coupling (viewing directionfrom the rear onto a vehicle),

FIG. 3 shows a side view of the trailer coupling,

FIG. 4 shows a cross section through the trailer coupling according toFIG. 2 along a cutting line A-A in FIG. 2,

FIG. 5 shows a perspective oblique view of the trailer couplingcorresponding approximately to FIG. 1, however with an alternativecoupling part,

FIG. 6 shows a schematic top view onto a rear end of a motor vehiclewith a carrier assembly, which has two trailer couplings according tothe invention, on which a load carrier is fitted, and

FIG. 7 shows a version of the trailer coupling according to theinvention, wherein the receiving sleeve is fastened to the retainer partby means of a flange assembly.

A trailer coupling 10 is attached to a motor vehicle 11 by means of acarrier assembly 12, for example. The carrier assembly 12 comprises across member 13, which extends transverse to the longitudinal directionof the motor vehicle 11 at the rear or behind the rear end 14 of themotor vehicle 11. A retainer 10 is arranged on the cross member 13,which is screwed, welded or firmly attached to the cross member 12 [sic]in another manner. The cross member 13 is fastened to the motor vehicle11, in particular the bodywork thereof, or screwed thereto by means ofside bars or fastening console (not shown).

The cross member 13, in particular in combination with the side barsand/or fastening consoles, and the carrier assembly 12 can form parts ofthe trailer coupling 10 according to the invention.

The retainer 20 serves to retain a coupling arm 14, which is detachablyfastened to the retainer 20. The retainer 20 has a tubular body 12, forexample, on the receiving end 22 of which an insertion opening 23 of aretainer insertion receptacle 24 is provided. The coupling arm 15 withan insertion projection 33 can be inserted into the retainer insertionreceptacle 24.

The vehicle-side retainer 20 is advantageously hidden behind a bumper 16of the motor vehicle 11. The coupling arm 15 protrudes into the freearea behind the rear end 14 or the bumper 16 so that a trailer can becoupled or a load carrier can be fitted onto the coupling arm 15.

The coupling arm 15 is in two parts, wherein it has a retainer part 30for fastening to the vehicle-side retainer 20 as well as a coupling part60 with a coupling element 65, for example a coupling ball, for couplinga trailer or load carrier. However, in a different embodiment, aninsertion receptacle or an insertion projection can also be provided ascoupling element 65 for attaching a load carrier, in accordance withFIG. 7 for example.

In addition to its insertion projection 33, the retainer part 30 haspositive locking contours 35 at the side, for example wedge-shapedpositive locking projections for engaging in corresponding positivelocking contours 25 of the retainer 20, for example, positive lockingreceptacles. The positive locking contours 25 fit with the positivelocking contours 35, therefore also configured wedge-shaped here. Thepositive locking contours 25 are located directly next to the insertionopening 23, for example. Thus, the retainer part 30 is held on theretainer in a rotationally locked manner.

A locking device 70 is used to lock the retainer part 30 onto theretainer 20. The locking device 70 comprises at least one, preferablytwo or three locking bodies 71, for example balls or other positivelocking elements. The locking body 71 engages in a locking receptacle ora plurality of locking receptacles 72 on the retainer 20. The lockingreceptacle or locking receptacles 72 are provided on a retaining body86, which is accommodated in a receptacle 26 of the retainer 20.

The locking receptacles 72 and the locking receptacle 72 can of coursealso be provided directly on the retainer 20.

The locking bodies 71 are supported on the retainer part 30 so as to bemovable, for example in guides 88. The locking bodies 71 can bedisplaced in the guides 88, which extend radially away from a channel87, by an actuation body 73 radially outwards in the direction of thelocking receptacle 72, for example a groove, in order to lock theretainer part 30 to the retainer 20.

The actuation body 73 is mounted on a longitudinal end of a bolt element74, for example, which has a toothed rack portion 75 on the otherlongitudinal end region. The bolt element 74 is accommodated in thechannel 87 in a longitudinally displaceable manner. The toothed rackportion 75 can be actuated by a gear pinion 76, for example. The gearpinion 76 can be rotated by means of a handle element 77, for example ahand wheel, in order to move the actuation body 73 in the direction of arelease position L, in which the locking body 71 does not engage in thelocking receptacle 72, or the locking position R, in which the lockingbody 71 engages in the locking receptacle 72. The locking position R isonly shown in the drawing in relation to the actuation body 73, which inthis case is moved further away from the gear pinion 76.

However, the locking device 70 only has to be actively actuated in thedirection of the release position L while a spring arrangement with aspring 78 acts in the direction of the locking position R. This isretained firstly on a step 79 in the channel 87 and secondly on theactuating body 73 so that it is spring-loaded in the direction of thelocking position R.

In the release position L, the locking device 70 can be retained bymeans of a securing device 80, which has an actuation lever 82, forexample. The actuation lever 82 actuates a locking pin 81, which engagesin a securing receptacle 85 on the bolt element 74 when this is movedinto the release position L. The actuation lever 82 is spring-loaded bya spring 84, which acts on a lever arm of the actuation lever 82, in thedirection of the securing position or the engagement position of thelocking pin 81 in the securing receptacle 85. When the retainer part 30is inserted into the retainer 20, the actuation lever 82 releases as itstrikes the retainer 20. In doing so, it displaces the locking pin 81from the securing receptacle 85 so that the spring 78 can actuate theactuation body 70 in the direction of the locking position R and thelatter thus moves the locking body 71 into the locking receptacle(s) 72.

The retainer part 30 has an arm section 31, which is attached to theretainer insertion projection 33 by means of a curved section 32. Thehand wheel or handle element 77 is arranged in the region of the curvedsection 32 for example.

The coupling part 60 can be attached to the retainer part 30. Thecoupling part 60 has an arm body 61, for example, on the free end region63 of which a coupling element 65, for example a coupling ball, isarranged. A coupling insertion projection 66 is located opposite thefree end region 63. A curved section 64 of an arm body 61 of thecoupling part 60 extends between the coupling insertion projection 66and the free end region 63.

A receiving sleeve 40 is provided on the retainer part 30, whichprovides a coupling insertion receptacle 41. The coupling insertionprojection 66 can be inserted into a free insertion opening 42 of thecoupling insertion receptacle 41.

The coupling insertion receptacle 41 has a stop 43 against which thefree end of the coupling insertion projection 66 strikes upon insertioninto the coupling insertion receptacle 41. The stop 43 is provided by astop element 47, for example, which protrudes from a peripheral wall 46of the receiving sleeve 40 to the internal cross section 44 thereof.

The internal cross section 44 of the insertion opening 42 and thecoupling insertion receptacle 41 is consistent with a cross section ofthe coupling insertion projection 66, for example rectangular in thepresent case, in particular squarish. In this case, corner regions,namely outer corners of the coupling insertion projection 66 as well asinner corners of the coupling insertion receptacle 41 are rounded sothat the coupling part 60 can be easily inserted into the receivingsleeve 40. The polygonal inner cross section 44 and the external crosssection of the coupling insertion projection 66 consistent therewith inan interlocking manner form an anti-rotation lock so that the couplinginsertion projection 66 cannot be rotated in the coupling insertionreceptacle 41.

A reinforcement ring 46 is arranged on a free front side 48 of thereceiving sleeve 40. This is mounted on the receiving sleeve 40 as aseparate component and fixed there, for example welded or glued. It isalso possible, however, that a tubular element, from which the receivingsleeve 40 is formed, is flanged or crimped on its front end or frontside 48 so that there is reinforcement in the region of the front side48 in any case.

The receiving sleeve 40 is accommodated in an attachment 27 of theretainer 20. The attachment 27 is bifurcate and has side arms 28. Anupper wall 49 of the receiving sleeve 40 is located at the base of theattachment 27. The arms 28 extend to side walls 50 of the receivingsleeve 40, approximately to a wall 51, which is opposite the wall 49,however not entirely.

Thus, a larger part of a cross section of the receiving sleeve 40 isaccommodated between the arms 28 or in the attachment 27 than thereceiving sleeve 40 protrudes from the arms 28.

The largest part of the receiving sleeve 40 or the largest cross sectionof the receiving sleeve 40 is accommodated in a receiving space 29 ofthe attachment 27.

In relation to a longitudinal extension LE of the arms 28, the receivingsleeve 40 only protrudes slightly from the arms 28 and is accommodatedmostly between the arms 28.

The arms 28 are wider in the region of the base of the attachment 27,but narrower at the free end regions thereof. The arms 28 thereforetaper away from the base of the attachment 27.

The attachment 27 and the retainer insertion projection 33 areadvantageously configured as a single piece. For example, the attachment27 forms a single piece with the arm section 31, which in turn forms asingle piece with the curved section 32 and the retainer insertionprojection 33. The attachment 27 and the retainer insertion projection33 are provided on a body 36, for example an arm body, of the retainerpart 30. The body 36 is preferably a cast part or forged part.

The receiving sleeve 40 advantageously comprises a tubular body or isformed by a tubular body.

The receiving sleeve 40 is glued, welded or secured in the attachment 27by means of a screw assembly. A welded seam 27 a is drawn in by way ofexample.

It would of course also be possible to provide a ring-shaped receptacle127 for the receiving sleeve 40 instead of the attachment 27, which isindicated schematically in the drawings.

The coupling part 60 can be locked onto the retainer part 30 by means ofa locking arrangement 90. Locking receptacles 91 opposite each other andflush with each other are located on the receiving sleeve 40, which areflush with a locking receptacle 92 of the coupling part 60 when thecoupling insertion projection 66 thereof is inserted into the couplinginsertion receptacle 41. A locking element 93, for example a bolt orsimilar, can then be inserted through the locking receptacles 91, 92 sothat the coupling insertion projection 66 can no longer be removed alongthe axis of insertion S2 thereof along which it is inserted into thecoupling insertion receptacle 41.

The locking arrangement 90 is easily accessible since it is provided ona section of the receiving sleeve 40 protruding from the retainerinsertion projection 33.

Furthermore, it is advantageous that the receiving sleeve 40 protrudesbackwards from the retainer insertion projection 33 in the direction oftravel of the motor vehicle 11, i.e. as shown in FIG. 1 advantageouslyprotrudes backwards from the bumper 16 from the motor vehicle 11.

The locking receptacles of a trailer coupling according to theinvention, for example the locking receptacles 91, 92 and/or an axis ofinsertion of the locking element therefore advantageously runtransverse, in particular at right angles to, the axis of insertionalong which the coupling insertion projection can be inserted into thecoupling insertion receptacle or removed therefrom.

The locking element 93 has an insertion section 94 through which thelocking receptacles 91, 92 are inserted. The locking element 93 can begripped easily on the operating section 95. The operating section 95 andthe insertion section 94 are angled relative to each other. A lockingpin, cotter pin or similar can be provided on the side of the insertionsection 94 opposite the operating section 95 in order to secure thelocking element 93 in an optimum manner and ensure its unwanted removal(not shown in the drawings however).

A coupling part 160 with its coupling insertion projection 166 can beinserted into the coupling insertion receptacle 41 instead of thecoupling part 60. The coupling part 160 has a coupling carrier 163, forexample, which has a protruding section 162. The section 162 isplate-shaped, for example. Thus, a bolt body 167, on the free ends ofwhich a coupling element 165 is arranged, can be inserted through apush-through opening of the section 162. The region of the bolt body 167protruding from the section 162 can be secured by means of a screw nut164.

The inventive concept is shown in FIG. 6 by means of a load carrier 200.The load carrier 200 has coupling insertion projections 266, forexample, which are arranged on the coupling parts 260 thereof.

Two retainers 20, for example, are arranged on a cross member 13, whichextends transversally at the rear end 19 of the motor vehicle 11 and isfastened to side bars 18 on the motor vehicle 11. The retainers 20 arearranged on the rear end 19 of the motor vehicle 11 at a transversedistance. Retainer parts 30 are inserted into each retainer 20. Theretainer parts 30 have coupling insertion receptacles 41 into which thecoupling insertion projections 266 of the load carrier 200 can beinserted.

The axis of insertion S2 along which the coupling projections 66, 166,266 can be inserted into the coupling insertion receptacle(s) 41,preferably runs in a substantially horizontal direction (in the useposition of the motor vehicle 11). On the other hand, an axis ofinsertion S1, along which the retainer insertion projection 33 is to beinserted into the retainer insertion receptacle 24, preferably runs atan angle to the axis of insertion S2, preferably in a substantiallyvertical direction.

A retainer part according to the invention can also have multiple partsas shown in FIG. 7 for example.

A retainer part 130 of a trailer coupling 110 corresponds substantiallyto the retainer part 30, but has no permanently fitted receiving sleeve,but rather a base part 159 and a receiving part detachably mounted onthe base part 15 and supporting a receiving sleeve 140. An arrangementof flange plates 150 with a flange part 151 arranged on an arm section131 of the retainer part 130 is provided for detachable fastening, whichflange part provides a supporting surface on the front side thereof, onwhich a supporting surface of a flange part 152 is supported. Areceiving sleeve 140 is arranged on a front side of the flange part 152facing away from the flange part 151, which corresponds geometricallyand functionally to the receiving sleeve 40, i.e. has a couplinginsertion receptacle 41 for the coupling part 60 or 160 and also thecoupling insertion projection 266.

The receiving sleeve 140 is on the rear side, i.e. supported on theflange part 152 on its rear side 142 facing away from the insertionopening 44.

The flange parts 150, 152 are screwed together by means of a screwassembly 157. The screw assembly 157 comprises screws 156, for example,which can be optionally screwed into screw receptacles 154 or screwreceptacles 155 on the flange part 151. Thus, the flange part 152 can befitted in at least two different longitudinal fitting positions M1 andM2 so that the receiving sleeve 40 and thus also the coupling insertionreceptacle 41 have the same different distances from a road surface O. Alongitudinal extension LX of the flange part 151 and/or 152 issufficiently long that the supporting surfaces 171, 172 of the flangeparts 151, 152 can support each other two-dimensionally and to asufficient extent in both longitudinal fitting positions M1 and M2.

It is clear that this design is also ideal for fastening the loadcarrier 200 at different heights relative to the road surface O. Thus,the retainer part 130 could be used instead of the retainer part 30 inthe arrangement according to FIG. 6 so that the load carrier 200 can bemounted on the motor vehicle 11 at different distances from the roadsurface O.

The invention claimed is:
 1. A trailer coupling for a motor vehiclecomprising: a retainer configured to be secured to the motor vehicle,the retainer comprising a retainer insertion receptacle and a lockingreceptacle; a retainer part detachably fastened to the retainer, theretainer part comprising: a retainer insertion projection configured tobe inserted into the retainer insertion receptacle, an integratedlocking device comprising at least one locking body and an actuationbody, wherein the at least one locking body interlockingly engages thelocking receptacle; a coupling arm comprising a coupling part comprisinga coupling element; a receiving sleeve comprising a tubular couplinginsertion receptacle, wherein the retainer part has a bifurcated orring-shaped attachment which holds the receiving sleeve.
 2. The trailercoupling according to claim 1, wherein the attachment comprises arms onthe sides against which walls of the receiving sleeve are attached. 3.The trailer coupling according to claim 2, wherein the receiving sleeveis attached on at least three sides of the attachment.
 4. The trailercoupling according to claim 1, wherein the retainer insertion projectionand the attachment are formed as an integral body.
 5. A trailer couplingfor a motor vehicle comprising: a retainer configured to be secured tothe motor vehicle, the retainer comprising a retainer insertionreceptacle and a locking receptacle; a retainer part detachably fastenedto the retainer, the retainer part comprising: a retainer insertionprojection configured to be inserted into the retainer insertionreceptacle, an integrated locking device comprising at least one lockingbody and an actuation body, wherein the at least one locking bodyinterlockingly engages the locking receptacle; a coupling arm comprisinga coupling part comprising a coupling element; a receiving sleevecomprising a tubular coupling insertion receptacle, wherein thereceiving sleeve is welded, glued or screwed to a bifurcate orring-shaped attachment of the retainer part accommodating the receivingsleeve.
 6. The trailer coupling of claim 5, wherein the receiving sleeveis reinforced by at least one reinforcing element.
 7. The trailercoupling of claim 6, wherein the at least one reinforcing elementcomprises a reinforcing ring arranged on a free front side of thereceiving sleeve.
 8. The trailer coupling of claim 5, wherein thetubular coupling insertion receptacle is configured to accept a couplinginsertion projection.
 9. The trailer coupling of claim 8, wherein thetubular coupling insertion receptacle and the coupling insertionprojection have at least one anti-rotation contour to receive thecoupling insertion projection in the coupling insertion receptacle inrotationally-locked manner.
 10. A trailer coupling for a motor vehiclecomprising: a retainer configured to be secured to the motor vehicle,the retainer comprising a retainer insertion receptacle and a lockingreceptacle; a retainer part detachably fastened to the retainer, theretainer part comprising: a retainer insertion projection configured tobe inserted into the retainer insertion receptacle, an integratedlocking device comprising at least one locking body and an actuationbody, wherein the at least one locking body interlockingly engages thelocking receptacle; a coupling arm comprising a coupling part comprisinga coupling element; a receiving sleeve comprising a tubular couplinginsertion receptacle, wherein the receiving sleeve is detachablyfastened to the retainer part.
 11. The trailer coupling of claim 10,wherein a manual actuation element is arranged on the retainer part formoving the actuation body towards a releasing position or a lockingposition.